Justification of Ecoregion Delineation"Cyclobalanopsis region" and "Castanopsis-Machilus region" on the Nihonkai side of Honshu (Miyawaki 1975), within the Japan Sea floral district in Shimizu (1975) which differentiates region with the mean annual maximum snow depth of 50cm. Roughly divided from the Taiheiyo side by the central mountain ranges.